Physical quantity detecting device and electric power steering apparatus using same

Abstract

A physical quantity detecting device that can determine abnormality of a signal transmission system between a physical quantity detector and a controller and an electric power steering apparatus using the physical quantity detecting device are provided. The physical quantity detecting device includes a physical quantity detector configured to detect a physical quantity and to output a physical quantity detection signal and a controller configured to receive the physical quantity outputted from the physical quantity detector via a transmission line and to perform a control operation on the basis of the physical quantity. The physical quantity detector outputs a diagnostic signal for detecting abnormality of a transmission system between the controller and the physical quantity detector and the controller includes an abnormality determining unit configured to determine abnormality of the transmission system on the basis of the diagnostic signal when receiving the diagnostic signal.

The invention claimed is: 
     
       1. A physical quantity detecting device comprising:
 a physical quantity detector configured to detect a physical quantity and to output a physical quantity detection signal; and 
 a controller configured to receive the physical quantity detection signal outputted from the physical quantity detector via a transmission line and to perform a control operation on the basis of the physical quantity, wherein 
 the physical quantity detector outputs the physical quantity detection signal and a diagnostic signal for detecting abnormality of a transmission system between the controller and the physical quantity detector to the controller via a noise filter, 
 the controller includes an abnormality determining unit configured to determine the abnormality of the transmission system on the basis of the diagnostic signal when receiving the diagnostic signal, and 
 the abnormality determining unit determines whether or not the noise filter is abnormal by detecting a change of at least one of a rise and a fall of the received diagnostic signal. 
 
     
     
       2. The physical quantity detecting device according to  claim 1 , wherein the physical quantity detector outputs the diagnostic signal for a predetermined period of time at a fixed period of time. 
     
     
       3. The physical quantity detecting device according to  claim 1 , wherein the physical quantity detector outputs a signal distinguishable from the physical quantity detection signal as the diagnostic signal. 
     
     
       4. A physical quantity detecting device comprising:
 a physical quantity detector configured to detect a physical quantity and to output a physical quantity detection signal; and 
 a controller configured to receive the physical quantity detection signal outputted from the physical quantity detector via a transmission line and to perform a control operation on the basis of the physical quantity, wherein 
 the physical quantity detector includes a signal switch configured to switch between the physical quantity detection signal and a diagnostic signal for detecting abnormality of a transmission system between the controller and the physical quantity detector and outputs the diagnostic signal at least at a time of power-up, 
 the controller includes an abnormality determining unit configured to determine the abnormality of the transmission system on the basis of the diagnostic signal when receiving the diagnostic signal, 
 the controller is configured to output a diagnostic signal output request to the physical quantity detector, and 
 the physical quantity detector outputs the diagnostic signal to the transmission line when receiving the diagnostic signal output request. 
 
     
     
       5. A physical quantity detecting device comprising:
 a physical quantity detector configured to detect a physical quantity and to output a physical quantity detection signal; and 
 a controller configured to receive the physical quantity detection signal outputted from the physical quantity detector via a transmission line and to perform a control operation on the basis of the physical quantity, wherein 
 the physical quantity detector includes a signal switch configured to switch between the physical quantity detection signal and a diagnostic signal for detecting abnormality of a transmission system between the controller and the physical quantity detector and outputs the diagnostic signal at least at a time of power-up, 
 the controller includes an abnormality determining unit configured to determine the abnormality of the transmission system on the basis of the diagnostic signal when receiving the diagnostic signal, 
 the physical quantity detector outputs a pulse-width modulated signal with a pulse width corresponding to the physical quantity as the physical quantity detection signal, and 
 the diagnostic signal is set to have a duty ratio out of an effective range of the pulse-width modulated signal. 
 
     
     
       6. The electric power steering apparatus comprising the physical quantity detecting device according to  claim 1 , wherein
 the physical quantity detector outputs a pulse-width modulated signal with a pulse width corresponding to the physical quantity as the physical quantity detection signal, and 
 wherein the diagnostic signal is set to have a duty ratio out of an effective range of the pulse-width modulated signal. 
 
     
     
       7. An electric power steering apparatus comprising the physical quantity detecting device according to  claim 1 , wherein
 the physical quantity detecting device detects at least one physical quantity necessary for calculating a steering torque command value and outputs the physical quantity detection signal and the diagnostic signal, and 
 the controller calculates the steering torque command value on the basis of the physical quantity detection signal of the physical quantity detecting device, and controls an electric motor generating a steering assist force on the basis of the calculated steering torque command value, and the abnormality determining unit determines whether or not the transmission system is abnormal when receiving the diagnostic signal.